Cucumber Mosaic Virus (hereinafter, referred to as “CMV”) is a plant-pathogenic virus having the widest host range of plant viruses, and causes great economic damage to about 900 kinds of dicotyledonous and monocotyledonous plants in the whole world. Plants infected with CMV show mosaic symptoms on leaves, stems and fruits. Particularly, the affected leaves become smaller in size and crumpled, and show lesions along leaf veins. Also, the affected fruits show dark-green mosaic patterns and become uneven, thus reducing product quality.
Meanwhile, in order to breed a disease-resistant variety, a disease-resistant factor should be introduced by successive backcrossing from other varieties having the factor. In each of the introduction steps, the disease-resistant factor should be selected through a resistance test, and in this selection step, the use of a molecular marker having a close association with the disease-resistant factor will make the selection very convenient. Thus, methods for the diagnosis of CMV using the molecular marker and various technologies for the development of CMV-resistant varieties by transformation have been developed. For example, Korean Patent Application No. 2000-0025699 discloses the nucleotide sequence of a set of gene amplification primers for the diagnosis of cucumovirus, in which the primer set allows the diagnosis of CMV, peanut stunt virus and tomato aspermy virus, which belong to the cucumovirus group, as well as a method for the diagnosis and identification of genes using the primers. Also, Korean Patent Registration No. 0293567 discloses a method for developing CMV-resistant tomato lines, which comprises transforming tomatoes with a CMV coat protein gene isolated in Korea. Furthermore, Korean Patent Application No. 1993-0029605 discloses a hammerhead-type ribozyme which attacks the RNA of a CMV coat protein gene, in order to produce transgenic crops having resistance to CMV causing diseases in crops.
As described above, the prior art on the diagnosis of CMV resistance and on the development of CMV-resistant plants targets the CMV coat protein gene, and there is no report of the development of technology concerning a CMV-resistant factor which is inherent in plants.
Accordingly, there has been an urgent need for the development of a CMV resistance-associated molecular marker from plant lines having the CMV-resistant factor and for the development of a method for diagnosing CMV infection in plants using the developed molecular marker.